1. Field of the Invention
The present invention relates to a recording method for dye-based recordable DVD medium in which information can be recoded and additionally recorded by irradiating a dye-based recordable DVD medium with a light beam to induce optical changes such as transmittance and reflectance to the recording layer thereof, and also relates to a recording apparatus.
2. Description of the Related Art
Presently, recordable digital versatile discs (DVD-R) are developed as next-generation large capacity optical discs. As essential technologies to enhance recording capacity of optical discs, it is necessary to develop recording materials to micronize recording pits, to employ image compression formatting technologies as typified by MPEG2, and to develop technologies for shortening the wavelength of semiconductor lasers for reading recording pits.
Conventionally, as for semiconductor lasers of the red wavelength region, only AlGaInP laser diodes each having a wavelength of 670 nm such as for barcode readers or instrumentation units have been commercialized. With high-densification of optical discs, red lasers are increasingly used in the optical storage market. DVD drives are standardized using laser diodes with two wavelengths of 635 nm and 650 nm for their light sources. In the meantime, DVD-ROM (Read Only Memory Digital Versatile Disc) drives are commercialized with a wavelength of about 650 nm.
Typically, in a dye-based recordable DVD medium where pits (marks) are formed by use of heat mode, the pulse width and the recording power of a recording pulse train are optimized by emission of a laser during recording at a specific recording speed, thus there exist a problem that the condition of marks and spaces to be formed is changed at different recording linear velocities. In other words, dye-based recordable DVD media suffer from problems that the jitter values tend to be higher, because thermal capacity of leading heating pulses required to form marks turns into insufficient, and the heating temperatures are varied relative to the optimal decomposing temperature to attain, resulting in variations in average mark lengths, and uniform mark widths cannot be obtained due to varied duty ratio of optimum heating pulse, resulting in thin marks or thick marks formed depending on the mark lengths.
With respect to physical formats of DVD media, DVD-R media are standardized with a format of which the land portions of so-called land pre-pits are partially cut. According to the format, there are problems that when a land pre-pit signal (LPPb) is less than 0.16, pre-pit information such as pre-pit address cannot be properly reproduced; in contrast, when a land pre-pit signal (LPPb) is more than 0.32, the land-pit signal itself behaves noisily at data region, thus resulting in frequent occurrences of data errors. Accordingly, there is a disadvantage that the land cut width needs to be finely adjusted to each recording material by the use of a stamper, and the land cut width needs to be adjusted so as to control the land pre-pit signal within the range of 0.16 to 0.32.
In order to solve the above-noted problems associated with conventional technologies, the present applicant has filed Japanese Patent Application Laid-Open (JP-A) Nos. 2004-303400, 2004-303401, 2005-100579, 2005-243202, 2005-243208, and 2005-293816 as technologies focusing attention on recording information on a dye-based recordable DVD medium with one pulse as well as with the waveform used when performing high-speed recording, however, all these applications differ in means for solving problems from the present invention.
Optical recording media each using a dye for the recording layer therein known in the art are too numerous to enumerate. Examples of such optical recording media include the one using a polymethine dye or using a polymethine dye and a light stabilizer as recording materials; the one having a layer containing a tetraazaporphyrin (porphyradine) dye or a cyanine dye and an azo metal chelate dye (salt forming dye) and a reflective layer as the recording layer; the one using a formazan (metal chelate) dye and other dyes as recording materials; and the one using dipyrromethene (metal chelate) dye and other dyes as recording materials. In addition, a number of optical recording media which perform multi pulse recording using a dye as a recording material are known in the art, however, as far as the present inventors know, literature focusing attention on recording information on a dye-based recordable DVD medium with one pulse as well as with the waveform used when performing high-speed recording like the present invention has not been found so far.